1. Field of the Invention
The present invention relates to an apparatus and method for detecting a tap.
2. Description of the Related Art
Various sensors are developed that detect the motions of persons or objects electrically or magnetically and output analog signals and/or digital signals.
Examples of these sensors include acceleration sensors, angular velocity sensors, gyro sensors, geomagnetic sensors, and optical sensors, which are based on various principles.
The acceleration sensors, the angular velocity censors, and the gyro sensors are commonly called inertia sensors because they measure inertial force. Recently, technologies are continuously developed that measure an acceleration sensor and an angular velocity sensor simultaneously and apply the measurements to various applications.
Among various functions, the inertia sensors have a function of detecting a tap or click.
Generally, a tap motion may be understood as a motion of shaking a device including an inertia sensor. Like the principle of mouse click input, a tap motion may be processed as a predetermined input value in a host device to which an inertia sensor is connected.
Due to the advent of various mobile devices and mobile device applications, a tap detection function for detecting a tap motion is used as one of the important functions of an inertia sensor.
Patent Document 1 discloses a technology for detecting and determining a tap or a double tap.
However, in detecting a tap, only when the amplitude of a sensor output signal is greater than a predetermined amplitude threshold (A_TH) and the sensor output signal is maintained for more than a predetermined duration threshold (D_TH), the technology of Patent Document 1 determines the occurrence of the tap and outputs the result.
FIGS. 1A to 1D are diagrams illustrating the relationship between a sensor output signal, an amplitude threshold and a duration threshold according to a conventional tap detection condition. The problem of a conventional tap detecting method like that of Patent Document 1 will be described below with reference to FIGS. 1A to 1D.
FIG. 1A illustrates the case where a tap is detected when the amplitude threshold condition and the duration threshold condition are satisfied.
FIG. 1B illustrates the case where the amplitude threshold condition is satisfied but the duration threshold condition are not satisfied. FIG. 1C illustrates the case where the duration threshold condition is satisfied but the amplitude threshold condition is not satisfied. FIG. 1D illustrates the case where the amplitude threshold condition and the duration threshold condition are not satisfied.
Referring to FIGS. 1A to 1D, the conventional tap detecting method has a low detection rate because it fails to detect a tap event in the event of a tap signal because it fixes the amplitude threshold and the duration threshold at predetermined values.